Data storage with rate correction



Sept. 28, 1965 Filed March 28, 1952 J. W. DOWNS DATA STORAGE WITH RATECORRECTION 5 Sheets-Sheet 1 INVENTOR JOHN W. D0 vv/vs X BY/WW ATTORNEYSept. 28, 1965 J. w. DOWNS 3,209,133

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DELAY LINE V86 70 Y X' 1/38 RATE STD/W965 SELECTOR CIRCUIT INVENTOR(JOHN W. D0 W/vs ATTORNEY United States Patent 3,209,133 DATA STORAGEWITH RATE CORRECTION J hn W. Downs, Glen Cove, N.Y., assignor to SperryRand Corporation, a corporation of Delaware Filed Mar. 28, 1952, Ser.No. 279,231 9 Claims. (Cl. 235179) This invention relates to electroniccomputing circuits and more particularly to data storage circuits withrate correction.

In the computing field there is frequently a need for apparatus whichwill receive and store a multiplicity of different data, and which iscapable of sorting out this data and of predicting future data. Forinstance, in an automatic search and tracking radar system, a great manysignals are received from various targets and it is necessary to selectthe received data pertaining to a particular target which it is desiredto track. It is also desirable to compute the rate of change of thisparticular data with respect to time, so as to predict the position ofthe target in the intervals between receiving data, and also as an aidto correlating new data with already received data. In certain cases,the data is not of a periodic nature but it is received in an irregularor aperiodic manner which factor complicates sorting and predictingfunctions.

Therefore, the primary purpose of the present invention is to providemeans to receive a multiplicity of different data, and means to sort andextrapolate the data so as to provide a continuous indication. The datamay be aperiodic and received in no specified order or time sequence.

The general outline of the invention is as follows. Old data is storedin a storage circuit and new data is continuously compared to theparticular stored data that is of interest. When a new reading isreceived from the particular target under consideration, the new data isalso stored. The difference between the old and new data is obtained anda time function of this difference is also obtained. This time functionis the change of the data with respect to time, and it is added to thelast received data in order to predict the occurrence of further newdata. When further data is received, it is also compared with thecontinually corrected, i.e. predicted data, and a time function of thedifference is taken. These steps are continually repeated so that thereis always present a continual corrected approximation of the targetposition. Sorting or selecting circuits and time function circuits areprovided so that the data need not be periodic and need not be receivedin any particular sequence.

The time function circuit may be a motor driven potentiometer to which adifference function is supplied. The output of the potentiometer is aproportional part of the difference voltage which is a function of time.The potentiometer may be driven at a predetermined rate by a constantspeed motor, or for more accurate work the rate of speed may be variedin accordance with the rate of change of the data.

Therefore, the present invention performs the following functions.

(1) It recognizes new data samples associated with stored data i.e. aselected target.

(2) It discards the old data and retains the new.

(3) It continually corrects the data last received.

The system may be used with single dimensional data for instancealtitude, or it may be expanded to utilize multidimensional data, forinstance, bearing and range, or even bearing, range, and altitude.

A principal object of the invention is to obtain a voltage which is afunction of the difference between old and new data with respect totime.

Another object of the invention is to predict new data based on the timerate of change of preceding data.

3,Zfi9,l33 Patented Sept. 28, 1965 Another object of the invention is tostore various different data and to sort out and select new data bycomparison with its related old data.

Another object of the present invention is to obtain a quantityproportional to the time rate of change of aperiodic data.

Another object of the invention is to store and continuously correctmulti-dimensional data.

Another object of the invention is to store different multi-dimensionaldata, to correlate new data with its corresponding stored data and makecontinual corrections of the stored data.

Another object of the present invention is to store multi-dimensionaldata in which the stored data is continually corrected at a calculatedrate.

Another object of the invention is to store aperiodic multi-dimensionaldata in which the stored data is continually extrapolated at acalculated rate.

Another object of the invention is to store data, correlate new datawith its corresponding old data and predict further new data.

Another object of this invention is to provide means for selecting adesired set of data from an ensemble of data in which the desired set ofdata have no degree of periodicity, either in time or sequence.

Another object is to provide means for sorting data in more than onedimension, such as two or three dimensional radar data.

Another object is to provide means having a variable tolerance on theerror of the datum that is to be accepted, so that the error in onedimension may be made to modify the tolerance on acceptance in anotherdimension.

Another object is to provide means for predicting the future position ofthe desired N-dimension datum from past aperoidic samples of data.

Another object is to provide means for continuously indicating theinstantaneous prediction of the data between the points of acceptingactual data.

These and other objects may be better appreciated from the followingspecification and figures of which:

FIG. 1 is a graph illustrative of the operation of the invention;

FIG. 2 is a schematic block diagram of a bridge type sorting circuit;

FIG. 3 is a schematic block diagram of an embodiment of the presentinvention;

FIG. 4 is a schematic diagram of an embodiment of the invention;

FIG. 5 is a graph illustrative of the invention;

FIG. 6 is a diagram of a relay adapted to be used in the invention; and

FIG. 7 is a schematic diagram of a voltage storage circuit.

FIGURE 1 is a graph showing plotted data. Particular old data is shownat x and the new data shown at x. The difference between x and x is thechange of voltage dx. A difference in time between the old and new datais the change of time d2. The rate of change of data with respect totime dx/dt is added to the new data value to produce a predicted valueas shown by the line 30. The next data received is platted at x". Thevalue of x will be identified as associated with the target, since it isclosely related to the locus 30 of the predicted value. At the time whenthe data x is received, it is compared with x and a new rate is computedwhich is used to provide a new prediction shown by the line 31. It isnoted that the data need not be received in periodic fashion.

FIGURE 2 shows a schematic sorting circuit with simplified switching.Data is received on input 35 and applied through the switches 24 and 22or 23 to one of the x storage and rate correction circuits 37 or 38. Inthe switch position shown, the circuit 38 is storing the old data andthe circuit 37 is sampling the new data. When new data is received whichis closely related to the old data as corrected the balance detector 40is energized. Thebalance detector 46 energizes relay 41, to actuate theswitches 21, 22, 23 and 24. Thus, the storage circuit 37 now stores thedata and the voltage storage circuit 38 is now available to receive orsample new data. Before a storage circuit is switched from storage tosample position, it is discharged and erased by switches 42, 43.

The Y-storage circuits 47 and 48 are adapted to store data in the seconddimension and operate exactly the same way as the X storage circuits 37and 38. The Y switching units are identical and are not shown. Thebalance detector 40 may be made responsive to the comparison of valuesin one dimension only, or may be made responsive to the comparison ofthe combination of values of two dimensions by means of switches 49, 49.This will be discussed more fully in connection with FIGURE 5. Thebalance detector 40 may be a relay which is energized when its inputsare made equal as will be shown more fully.

FIGURE 3 shows a schematic block diagram of a bridge type circuit likeFIGURE 2 which provides an output on lead 52 which is continuallycorrected at a calculated rate. In this embodiment the speed of themotor 55 is varied by rate selector 59 so it will provide a closeapproximation of the predicted value than the embodiment of FIGURE 1,for instance, where the motor is driven at a predetermined averagespeed. Otherwise, the circuit of FIGURE 3 operates generally the same asthat of FIG. 2.

There are four storage circuits provided in a bridge arrangement as inFIGURE 2. These four circuits are X storage circuit 37, the X storagecircuit 38, the Y storage circuit 47 and the Y storage circuit 48. Thebalance detector 40 is responsive to Y data or to the sum of the X and Ycomponents depending on switches 49, 49. The X switching and ratecorrection circuits are not shown since they are the same as the Ycircuits shown. When the voltages appearing across the balance detector40 are equal, its output will be energized, thereby providing a signalto relay 51 which operates the input switches 27, 28, output switch 26,and to the rate selector 59 which controls the speed of motor 55. Themotor rotates the potentiometers 56 and 57 proportionately to thedifference between the last two data.

FIGURE 4 shows a schematic diagram of the circuit of FIGURE 3 showingthe details of the rate selecting comparison means 59 and the balancedetector 40. The data input is received on lead 60 and connected throughswitches 61 and 62 to the appropriate storage circuit. The input isshown connected to the Y storage circuit 47 since the switch 61 is inthe sample position. The Y storage circuit 48 is in storage position andhas the previous old data stored on the condenser 63. The voltage acrosscondenser 63 is corrected at a rate proportional to the differencebetween the last two pieces of data received. This rate is determined bythe rate selector 59 which functions as a comparison means.

The rate selector 59 comprises a pair of condensers 65, 66 which sampleand store the outputs from storage tubes 47 and 48 respectively.Therefore, condenser 65 will store a first piece of data and condenser66 will store the next one. Voltages proportional to the voltages oncondensers 65 and 66 are taken from the cathode followers 65' and 66'and applied to the motor 11 in a differential manner. The rate selector59 is therefore seen to be a comparison means by which selected data arecompared and the speed of the motor is controlled by the output of thecomparison means so as to be proportional to the difference between thelast two selected data. The motor drives the potentiometers 67 and 68,which provide a correction voltage which is proportional to time. Thecorrection from potentiometer 68 is added to the stored voltage oncondenser 63. This corrected voltage is then taken at the output ofcathode follower 48 and connected to one side of output switch 70.

The other portion of the output switch 70 is connected to the Y storagecircuit comprising cathode follower 47 and condenser 71 andpotentiometer 67 which operates in the same manner. The balance detector40 is connected between the outputs of Y storage circuit 47 and Ystorage circuit 48 and is adapted to provide a pulse signal when thevoltages at its two inputs are equal. The balance detector may be maderesponsive to both the X and Y components by connecting switch 49 and43.

The balance detector 40 comprises a relay having a pair of oppositelywound coils 72, 73 connected in parallel. Oppositely poled rectifiers 74and 74' are each connected in series with one of the coils so that theunbalance current may How in either direction to hold the relay open.There will normally be an unbalance current flowing so that the relay 75will be open and the condenser 76 will be charged to some value bybattery 87. Therefore, when a balanced condition occurs at the twoinputs the relay 75, which may be spring loaded by spring 69, is closedmomentarily and the condenser 76 will discharge providing a pulsedoutput to operate the switching relays.

The pulse from the balance detector 40 will energize relay coil 80 intre rate selector to momentarily close the contacts 81 and 82 to correctthe voltages on condensers 65 and 66. The pulse of the balance detectorwill also energize relay 84 which is the erasing relay, the function ofwhich is to erase the voltage storage circuits as they go from storageto sample position. The pulse from the balance detector also energizesthe relay coil 85 through delay line 96, which energizes the relays 61and 62, so that the relay 84 is in the proper position to erase thevoltage from the proper storage circuit. Delay could be introducedmechanically by providing the switches to be delayed with mechanicaldetents, and actuating them, by means of the spring connected to one ofthe undelayed switches, so that the action of the spring would be toincorporate a time lag in the operation of the delayed switches. Relays84 and 85 are of the flip-flop type which change their associatedswitches 84', 61, 62 and 70 from one contact to the other on the receiptof successive pulses. Their operation is like that of the familiar pullchain electric light switch. A suitable relay is shown in FIGURE 6.Relay operated clutches 53 and 54 operate to reset the potentiometers 67and 68.

The operation of the embodiments of FIGURES 3 and 4 may be summed up asfollows:

(1) X and Y coordinates of a radar target are stored as unbalancingsignals in two arms of a bridge.

(2) The opposite arms then sample a multiplicity of other data.

(3) When a set of coordinates approximately matching those stored arefound, the balance detector is actuated.

(4) The balance detector causes the rate selector to sample and storethe old and new data.

(5) The rate selector causes a motor to run at a speed proportional tothe change in position and also causes the bridge to reverse its inputand output circuits.

(6) In the reversing process the old datum is erased causing the bridgeto unbalance again.

(7) The process will now be continued. Meanwhile an output voltage isprovided which represents the last corrected target position plus alinear correction.

It is seen that the system operates by:

(1) recognizing the data samples associated with its stored data,

(2) discarding the old data and retaining the new, and

(3) continuously correcting the data last received.

Compared to conventional tracking circuits, the present circuit offers aparticular advantage in that its acceptance or rejection of a set ofcoordinate data is based on a more realistic standard. In theconventional circuit, where range and azimuth gates of predetermineddimensions are used, a particular datum falling outside either gatewould result in that set of coordinate data being lost. For example, inFIG. 5 the reported azimuth of a target might agree exactly with thatpredicted but the reported range might differ by some amount slightlyoutside the range acceptance gate. Thus that set of data would be lost.

In the present tracking channel, the X acceptance gate varies in widthdepending on the error in the predicted Y coordinate. If the Y error iszero, the X gate width is a maximum, and conversely. This is the resultof using the bridge technique in which balance is a complex function ofthe impedance of four circuits.

This conception is illustrated in FIGURE 5. Let the predicted course ofthe target be ABC, where B is the predicted position at the instant thecorrect position B is received. The area bounded by OR, OS, PP and QQ'represents a hypothetical range-azimuth gate. Although B is nearlycorrect in azimuth, it falls outside the range gate. In a conventionaltracking circuit, therefore, both datum coordinates would be lost. Inthe present combined gate method disclosed herein, the large error in ofthe new data point B is accepted because the error in Y is small.

While the present tracking system has been discussed in connection withthe tracking of X and Y coordinates only, it is applicable to thetracking of the altitude coordinate as well.

FIG. 6 illustrates a relay of the fiip-flop which is adapted to flipfrom one of two positions to the other, in response to an energizingsignal. The relay arm 90 is pivoted at the point 91 and has a weight 92of magnetic material at its free end. When the coil 93 is energized by apulse of energy the relay arm 90 rises from the left hand position andits momentum carries it over to the right hand position. Spring Moperates as a detent providing positive switch action. The next pulse ofenergy appearing on coil '93 will move the relay armature from the righthand position back to the left hand position. Therefore, the operationis like that of a flip-flop circuit and the position of the relayarmature 30 alternates from one extremity to the other in response topulses of energy on the energizing coil 93.

An alternative flip-flop relay might be a step relay of the type havinga plurality of contacts arranged in a circle and an arm which rotates insteps and responds to successive pulses. If alternate contacts wereconnected together, it would operate as a flip-flop circuit.

FIGURE 7 shows a typical storage circuit. The input is stored oncondenser 88 and also is applied to the grid of the vacuum tube 89. Theoutput is taken across the cathode resistor 83. The time constant andstability of the storage circuit is improved in a well known manner byproviding a feedback signal through feedback amplifier 77 from theoutside to the input of tube 85. The sequence of operation of the relaysis as follows. Samples are applied to the upper position of relay arm 78and when the proper value is chosen as previously explained, the relayarm is connected to the lower storing position. The storage circuit iserased by means of relay 79 which discharges the voltage on condenser 84before the relay 73 is returned to the sampling position.

Therefore, the present invention provides means for continuouslycorrecting multi-dimension data. The data is not required to be periodicor any particular time sequence. The invention is not limited to radarsystems but may be used in various types of computers such as those usedin the solution of gun fire problems, navigation problems or ballisticsproblems. The invention is not limited to computing but may be utilizedfor instance in inspection or quality control of physical items wheretwo or more characteristics of the items may be compared againststandard quantities. For instance, the present invention could be usedto compare the diameter and weight of ball bearings with standardquantities, the capacity and leakage of condensers against standardvalues, or the color and intensity of light from bulbs.

The present invention could also be used in the receiving equipment of adata transmission system where the transmitting link must be time sharedbetween several data generators and the continuous record of eachgenerator output provided at the receiver.

What is claimed is:

1. A data discriminator comprising a first pair of storage meansconnected in the conjugate arms of a bridge, a second pair of storagemeans connected in conjugate arms of said bridge, means to impress afirst series of successive data alternately upon each of said first pairof storage means, means to impress a second series of successive dataalternately upon each of said second pair of storage means, comparisonmeans connectably disposed to receive the data signals of said firstpair of storage means for producing an output signal proportional to thedifference therebetween, balance detector means connected betweenopposite junctions of said two pairs of conjugate arms and responsive toa determinable degree of unbalance between said first and second datafor connecting said first pair of storage means to said comparisonmeans, whereby said output signal is continuously corrected to reflectdata changes within the limits of said determinable degree of unbalance.

2. A data discriminator comprising a first pair of storage meansconnected in the conjugate arms of a bridge, a second pair of storagemeans connected in conjugate arms of said bridge, means to impress afirst series of successive data alternately upon each of said first pairof storage means, means to impress a second series of successive dataalternately upon each of said second pair of storage means, firstcomparison means connectably disposed to receive the data signals ofsaid first pair of storage means for producing a first output signalproportional to the difference therebetween, second comparison meansconnectably disposed to receive the data signals of said second pair ofstorage means for producing a second output signal proportional to thedifference therebetween, balance detector means connected betweenopposite junctions of said two pairs of conjugate arms and responsive toa determinable degree of unbalance between said first and second datafor connecting said first and second pair of storage means to said firstand second comparison means respectively, whereby said first and secondoutput signals are continuously corrected in accordance with respectivedata changes within the limits of said determinable degree of unbalance.

3. A data discriminator comprising a first pair of storage meansconnected in the conjugate arms of a bridge, a second pair of storagemeans connected in conjugate arms of said bridge, switching meansconnected to receive a first series of discrete aperiodic random dataand adapted to impress said data upon either storage means of said firstpair, switching means connected to receive a second series of discreteaperiodic random data and adapted to impress said data upon eitherstorage means of said second pair, first comparison means connectablydisposed to receive the data signals from said first pair of storagemeans for producing a first output signal proportional to the differencetherebetween, second comparison means connectably disposed to receivethe data signals from said second pair of storage means for producing asecond output signal proportional to the difference therebetween,balance detector means connected between opposite junctions of said twopairs of conjugate arms and responsive to a determinable degree ofunbalance between said first and second data for actuating said firstand second switching means, whereby said first and second output signalsare continuously corrected to reflect respective changes of data withinlimits of deviation dependent upon said determinable degree ofunbalance.

4. A data discriminator comprising a first pair of storage meansconnected in conjugate arms of a bridge, a

second pair of storage means connected in conjugate arms of said bridge,switching means connected to receive a first series of discreteaperiodic random data including actuation means adapted to impress saiddata upon either storage means of said first pair, switching meansconnected to receive a second series of discrete aperiodic random dataincluding actuation means adapted to impress said data upon eitherstorage means of said second pair, first comparison means connectablydisposed to receive data signals from said first pair of storage meansfor producing a first output signal commensurate with the rate of changeof successively selected first data, second comparison means connectablydisposed to receive data signals from said second pair of storage meansfor producing a second output signal commensurate with the rate ofchange of successively selected second data, balance detector meansconnected between opposite junctions of said two pairs of conjugate armsof said bridge, said balance detector being responsive to a determinabledegree of unbalance for generating a signal to actuate both saidswitching means to their alternate positions, whereby said first andsecond output signals are periodically corrected in accordance with therate of change of respective successive data selected within limitsdetermined by the combined rates of change of sequential data withinsaid first and second series.

5. A data discriminator in accordance with claim 4 including signalneutralizing means connected to receive said actuation signal, saidneutralizing means being arranged and disposed so as to be momentarilyconnected to the storage means having the oldest data before saidstorage means receives newly selected data.

6. A data discriminator in accordance with claim 4 including time delaymeans connected between said balance detector and said switching meanswhereby to delay said actuation signal, and signal neutralizing meansconnected to receive said actuation signal and adapted to be momentarilyconnected to the storage means having the oldest data.

7. A data discriminator in accordance with claim 4 including dischargemeans, said means being responsive to the criteria for selection of newdata to momentarily discharge the storage means having the oldest dataof that series from which the new data is selected.

8. A data discriminator comprising a first pair of storage meansconnected in conjugate arms of a bridge, a second pair of storage meansconnected in conjugate arms of said bridge, switching means connected toreceive a first series of discrete aperiodic random data includingactuation means adapted to impress said data upon either storage meansof said first pair, switching means connected to receive a second seriesof discrete aperiodic random data including actuation means adapted toimpress said data upon either storage means of said second pair, firstcomparison means connectably disposed to receive data signals from saidfirst pair of storage means for means for producing a first outputsignal continuously changing at the rate of change of successivelyselected first data, second comparison means connectably disposed toreceive data signals from said second pair of storage means forproducing a second output signal continuously changing at the rate ofchange of successively selected second data, balance detector meansconnected between opposite junctions of said two pairs of conjugate armsof said bridge, said balance detector being responsive to a determinabledegree of unbalance for generating a signal to actuate both saidswitching means to their alternate positions, whereby said first andsecond output signals extrapolate respective rates of change ofsuccessive data selected within limits determined by the combined ratesof change of sequential data of said first and second series.

9. A data discriminator comprising a first pair of storage meansconnected in conjugate arms of a bridge, a second pair of storage meansconnected to conjugate arms of said bridge, switching means connected toreceive a first series of discrete aperiodic random data includingactuation means adapted to impress said data upon either storage meansof said first pair, switching means connected to receive a second seriesof aperiodic random data including actuation means adapted to impresssaid data upon either storage means of said second pair, firstcomparison means connectably disposed to receive data signals from saidfirst pair of storage means for producing an output signal continuouslychanging at the rate of change of successively selected first data,second comparison means connectably disposed to receive data signalsfrom said second pair of storage means for producing an output signalcontinuously changing at the rate of change of successively selectedsecond data, means to continuously correct the last stored data signalsin each of said first and second pair of storage means with said firstand second output signals respectively, balance detector means connectedbetween opposite junctions of said two pairs of conjugate arms of saidbridge, said balance detector being responsive to a determinable degreeof unbalance for generating a signal to actuate both said switchingmeans to their alternate positions, whereby said first and second outputsignals extrapolate respective rates of change of successive dataselected within limits determined by the combined rates of change ofsequential data of said first and second series as compared to storeddata corrected in accordance with data signals continuously predicted byextrapolation.

References Cited by the Examiner UNITED STATES PATENTS 2,431,696 12/47Keister 235-179 2,473,457 6/49 Tyson 250-27 2,516,765 7/50 Ferrell3437.4 2,538,027 1/51 Mozley 3437.4 2,542,032 2/51 Isbister 34352,588,209 3/52 Crapuchettes 17195 MALCOLM A. MORRISON, Primary Examiner.

NORMAN H. EVANS, Examiner.

1. A DATA DISCRIMINATOR COMPRISING A FIRST PAIR OF STORAGE MEANSCONNECTED IN THE CONJUGATE ARMS OF A BRIDGE, A SECOND PAIR OF STORAGEMEANS CONNECTED IN CONJUGATE ARMS OF SAID BRIDGE, MEANS TO IMPRESS AFIRST SERIES OF SUCCESSIVE DATA ALTERNATELY UPON EACH OF SAID FIRST PAIROF STORAGE MEANS, MEANS TO IMPRESS A SECOND SERIES OF SUCCESSIVE DATAALTERNATELY UPON EACH OF SAID SECOND PAIR OF STORAGE MEANS, COMPARISIONMEANS CONNECTABLY DISPOSED TO RECEIVE THE DATA SIGNALS OF SAID FIRSTPROPORTIONAL TO MEANS FOR PRODUCING AN OUTPUT SIGNAL PROPORTIONAL TO THEDIFFERENCE THEREBETWEEN, BALANCE DETECTOR MEANS CONNECTED BETWEENOPPOSITE JUNCTIONS OF SAID TWO PAIRS OF CONJUGATE ARMS AND RESPONSIVE TOTHE DETERMINABLE DEGREE OF UNBALANCE BETWEEN SAID FIRST AND SECOND DATAFOR CONNECTING SAID FIRST PAIR OF STORAGE MEANS TO SAID COMPARISONMEANS, WHEREBY SAID OUTPUT SIGNAL IS CONTINUOUSLY CORRECTED TO REFLECTDATA CHANGES WITHIN THE LIMITS OF SAID DETERMINABLE DEGREE OF UNBALANCE.